1. Field of the Invention
The present invention relates to an organic electroluminescent device comprising a transparent moisture absorption layer that can be used in a front emission type device and a method for manufacturing the organic electroluminescent device.
2. Description of the Background
Organic electroluminescent devices may easily deteriorate as a result of the permeation of moisture. Therefore, an encapsulation structure is required to ensure stable driving and an extended lifetime of an organic electroluminescent device.
Conventionally, a metal can or a glass substrate formed into a cap with a groove is used in an organic electroluminescent device. For moisture adsorption, a desiccant powder is mounted in the groove or a desiccant film is adhered to the groove with double-sided tape.
Japanese Laid-Open Patent Publication No. Hei 9-148066 discloses an organic electroluminescent device that includes a laminate having a pair of electrodes facing each other with an organic light-emitting material layer made of an organic compound interposed between the electrodes. The device also includes an airtight container for preventing exposure of the laminate to air and drying means made of, for example, alkali metal oxide, disposed in the airtight container. However, the bulky structure of the airtight container increases the total thickness of the organic electroluminescent device. Also, the opaqueness of the drying means renders the fabrication of a front emission type organic electroluminescent device difficult, even though the drying means is maintained in a solid state after absorbing moisture.
U.S. Pat. No. 6,226,890 describes an organic electroluminescent device that includes a moisture absorption layer produced using a desiccant and a binder. The moisture absorption layer contains solid particles with a particle size of 0.1-200 μm.
However, the organic electroluminescent device is translucent or opaque, and thus cannot be used as a front emission type device, and also has low moisture absorption ability.